Single-shaft switching device

ABSTRACT

In a shifting system ( 2 ) for a vehicle transmission which comprises a shifting shaft ( 6 ), at least one gear change hub ( 18 ) is movably placed in a transmission housing ( 4 ) upon the shifting shaft ( 6 ). The shifting shaft ( 6 ) has at least one shifting pin ( 30 ) which with the shifting shaft ( 6 ) is rotatable around an axis of rotation ( 12 ) and which with the shifting shaft ( 6 ) is movable along the axis of rotation ( 12 ). Depending on the position of rotation of the shifting shaft ( 6 ), the shifting shaft ( 6 ) moves with the shifting pin ( 30 ) the gear change hub ( 18 ). The shifting pin ( 30 ), which upon shifting moves the selected gear change hub ( 18 ), is placed outside the gear change hub ( 18 ) and engages in a bracket ( 46 ) connected with the gear change hub ( 18 ) and projects from the gear change hub ( 18 ). On the outer surface, the gear change hub ( 18 ) has one slot ( 34 ) in which a locking device ( 36, 38, 42 ) is slidingly placed.

According to the preamble of claim 1, the invention concerns a shiftingsystem having one shifting shaft.

Different systems are known for shifting vehicle transmissions. U.S.Pat. No. 6,026,702 shows a shifting system having only one shiftingshaft for six gears of which one gear can be a reverse gear. In theseparate shifting forks, spring-mounted pins engage with which theshifting forks can be locked in a determined position relative to thetransmission housing. On the inner side of the part of the shifting forksituated upon the shifting shaft and penetrating the shifting shaft,apertures and slots are provided in which the pins can move. At the sametime with each shifting fork is associated one pin which, by rotation ofthe shifting shaft, can engage in the shifting fork in a manner, suchthat in a certain torsional position of the shifting shaft, the shiftingfork is moved along when the shifting shaft axially moves. For thispurpose by the pin one other pin which, as a locking pin, carries out alocking function and sits in the transmission housing, is pressed intothe transmission housing against the pressure of a spring and releasesthe shifting fork so that it can be axially moved. For penetrating thelocking pin, one other aperture must be provided in the shifting fork sothat in the shifting fork, together with the four slots for guiding thepin connected with the shifting shaft in the non-shifted state of theshifting fork, still one other aperture is provided for the locking pin.In the area of the aperture, the shifting fork is then also additionallymachined so that the locking pin can be pressed by the spring into threedifferent recesses which correspond to the current shifting state of theshifting fork. The shifting fork, made of high quality material or atleast the guide thereof into the shifting shaft, must therefore beprocessed during the production stage so that the four slots, theaperture for the locking pin and the recesses of the locking pin can beput in place. This means high expenditure in finishing technique whichrequires both time and financial resources.

The problem on which the invention is based is to indicate a shiftingsystem which is easy to produce and can be used of different shiftingforks or shifting rocking arms.

The problem is solved by a shifting system having the features of claim1. Developments are the object of sub-claims.

According to the invention, it is provided to produce a shifting systemfor a vehicle transmission in a transmission housing which comprises oneshifting shaft for all gears to be shifted and upon which at least onegear change hub is movably placed. Within the gear change hub, theshifting shaft can be rotated and has at least one shifting pinrotatable with the shifting shaft around an axis of rotation. Likewise,the shifting pin is movable with the shifting shaft along the axis ofrotation. Depending on the rotation of the shifting shaft, the shiftingshaft can move the gear change hub with the shifting pin. The shiftingpin, which upon shifting, moves the selected gear change hub situatedoutside the gear change hub. Thereby the inner bore of the gear changehub is processed only for the gear change hub to the shifting shaft andhas no grooves or slots like the shifting forks of the prior art. Theprocessing of the gear change hub is thereby substantially simplifiedand can be equally designed for every kind and size of shifting forks orshifting rocking arms. For this purpose, the shifting fork must beconnected only with the adequately shaped, shifting fork of the shiftingrocking arm. The gear change hub can be made integral with a shiftingfork or shifting rocking arm, but it can also be made as a separate partand then connected with the shifting fork or shifting rocking arm by anadequate process, such as welding or screwing. In an advantageousdevelopment, the shifting pin engages in a bracket connected with thegear change hub and projecting from the gear change hub which can alsohave recesses in which engages one detent element in the currentshifting position. The detent element advantageously comprises a coilspring which supports itself against the transmission housing and therepresses a piston into the relevant recess. The bracket is preferablyfastened on the gear change hub with at least one connecting element,such as a screw or a rivet. In one development, the bracket is directlycast in the gear change hub. In an advantageous development, the gearchange hub has a slot on its outer surface in which a locking device isslidingly placed. The locking device comprises a sliding rail, a lockingpin situated on the sliding rail and engaging in the gear change huband, opposite the shifting pin and situated on the sliding rail, areceptacle for a spring element. The spring element supports itself onthe transmission housing and presses the shifting pin situated on thesliding rail in a direction toward the gear change hub into a recessformed in the slot of the gear change hub. The receptacle for thatpreferably forms one sleeve in which a coil spring is situated as springelement. In an advantageous development, the shifting pin, lying outsidethe gear change hub and associated with the gear change hub that must beengaged, also actuates the locking device on the gear change hub thatmust be shifted at the time. In an especially advantageous design, allgear change hubs, all locking devices and all brackets projecting fromthe gear change hub have the same shape. This considerably reduces theexpenditure in parts of different kinds in the transmission. The gearchange hub can advantageously be connected with a shifting fork or witha shifting rocking arm or part of such a shifting fork or shiftingrocking arm. In a particularly advantageous development, the gear changehub and, optionally, the shifting fork or the shifting rocking arm aremade of a plastic material while the shifting pin in the shifting shaft,the bracket and the locking device consist of metal.

An essential advantage of the shifting system consists in its modularconstruction. Thereby the bracket projecting from the gear change hub,the locking devices, the gear detent, the shifting pin, the support ofthe shifting shaft and, optionally, the gear change hub can be used forany kind of automatic transmission. Only the length of the shiftingshaft, the arrangement of the shifting pins upon the shifting shaft andthe relevant shifting forks or shifting rocking arms, either as completeelement placed upon the shifting shaft or as partial element connectedwith the gear change hub, have to be changed and adapted to the currentrequirements.

The invention is described in detail with reference to drawings whichshow:

FIG. 1 is a side view of the shifting system;

FIG. 2 is a view on the shifting system;

FIG. 3 is a section through a shifted shifting fork;

FIG. 4 is a section through a non-shifted shifting fork;

FIG. 6 is a view on a bracket;

FIG. 7 is a locking device; and

FIG. 8 is a shifting pin.

FIG. 1 is a side view diagrammatically showing the shifting system 2 ina transmission housing 4 (not shown in detail). A shifting shaft 6 issupported in the transmission housing 4 on two bearings 8 and 9 so as toallow the shifting shaft 6 to rotate around an axis of rotation 12 andaxially to move along the axis of rotation 12 for which purposesufficiently large apertures are provided in the transmission housing 4.The shifting shaft 6 is rotated and moved by a gear shift mechanism 14(not shown in detail), which is connected with a manual gear changelever (not shown) or an automated actuator. Upon the shifting shaft,three gear change hubs 16, 18 and 20 are placed which, in the exampleshown here, are designed in one piece with three shifting forks 22, 24,26. The shifting shaft is penetrated by three shifting pins 28, 30 and32, such as shown in detail in FIG. 8 and FIG. 2. One shifting pin 28,30, 32 is associated with each shifting shaft 22, 24, 26, the relevantshifting pin not situated within the associated gear change hub, butbeing located outside the associated gear change hub at a specificdistance from the gear change hub. In a slot 34 on the gear change hub16 is located a sliding rail 36 wherein the gear change hub 16 beaxially moved along the axis 12 and the sliding rail 36 is retainedaxially firmly in the transmission housing via a sleeve 38. A coilspring 40 (FIG. 2) placed within the sleeve 38 presses the sliding rail36 in direction to the gear change hub 16, i.e. in directionperpendicular to the drawing plane in FIG. 1. A locking pin 42 issituated on the sliding rail 36, which can engage in a recess 44 on thegear change hub 16 thereby preventing the axial movement of the gearchange hub 16. The other gear change hubs 18 and 29 (shown) havecorresponding devices, the illustrations for the gear change 16representing them.

In FIG. 2, by way of example, for all gear change hubs is shown abracket 16 placed on the gear change hub 18, as shown in detail in FIG.5 and in FIG. 6. The bracket 46 is fastened on the gear change hub 18and is movable together with it. The fastening is made, e.g., directlyduring the manufacturing process of the gear change hub by bracket 46being cast with the gear change hub 18 or the bracket being fastened onthe gear change hub 18 by fastening elements such as screws 50. Thebracket 46 can consist here, e.g., of a sintered metal material. Thebracket 46 has one aperture 48 in which the shifting pin 30 can engageand through which shifting pin 30 can be guided during a rotation of theshifting shaft 6. In bracket 46, three recesses 52, 54 and 56 areprovided in which the piston 58 of a detent device can optionallyengage. In the position shown in FIG. 2, the piston 58 engages in therecess 54, which corresponds to a middle position or neutral position ofthe gear change hub 18. In this position, no gear is changed by the gearchange hub 18. The recesses 52 and 56 lying next correspond to the twoopposite gear change positions of the gear change gate. In thesepositions, the gear change hub 18 and, thereby the shifting fork orshifting rocking arm connected therewith, is held by a piston 58. Forthis purpose, the piston 58 is pressed into the relevant recess by acoil spring 60 which supports itself against the transmission housing 4.For axial movement of the bracket 46 and of the gear change hub 18, thetension of the coil spring 60 has to be overcome. In a torsionalposition of the shifting shaft 6, the shifting pin 30 stands by a point62 precisely in the aperture 48 of the bracket 46. If the shifting shaft6 is now axially moved along the axis 12, the shifting pin 30 with itspoint 62 takes along the bracket 46 in the direction of movement of theshifting shaft 6. During the axial movement of the bracket 46, thepiston 58 is pressed out of one of the recesses against the tension ofthe coil spring 60 and releases the bracket 46 at the same time. Thepiston 58 then slips into the adjacent recess after the bracket 46 hasaxially moved as far as the distance of the recesses allows. In thetorsional position of the shifting pin 30, in which it is in position toaxially move the bracket 26, the other point 64 of the shifting pin 30located opposite the point 62 presses the sliding rail 36 against thetension of the coil spring back in direction of the transmission housing4. Thereby the locking pin 42 is pressed out of the recess 44 andreleases the gear change hub 18 for axial movement. Therefore, theshifting pin 30 serves simultaneously for engaging the desired gear andunlocking the gear change hub to be engaged.

FIG. 3 shows a shifting fork 66 which is made integral with the gearchange hub 18. The shifting shaft 6 is rotated so that in the positionshown the gear change hub 18 can be moved by the shifting shaft 6perpendicularly to the plane of the drawing. The point 62 of thehorizontally lying shifting pin 30 engages in the bracket 46 and thepoint 64 of the shifting pin 30 presses the sliding rail 36 with itssleeve 36 to the right against the spring 40 in the drawing plane.Thereby the locking pin 42 no longer engages in the gear change hub 18but lies free in the recess 44. The aperture 48 in the bracket 46 inwhich the shifting pin 30 engages with its point 62 has sloped surfaces68 so that the point 62 can more easily thread into the aperture 48. Thesliding rail 36 likewise has in the area of the point 64 of the shiftingpine 30 sloped surfaces 70 in order that during torsion of the shiftingshaft 6 the point 64 can more easily press back the sliding rail 36.

FIG. 4 shows the arrangement of FIG. 3 with a shifting shaft 6 turnedfor the purpose. The point 62 no longer lies in the aperture 48 and thepoint 64 of the shifting pin 30 no longer presses upon the sliding rail36. Thereby the locking pin 42 engages in the gear change hub 18 andblocks its freedom of axial movement. In this position, the gear changehub 18 cannot be moved by the shifting shaft 6 perpendicularly to thedrawing plane but is locked relative to the transmission housing.

FIG. 5 and FIG. 6 show a partly enlarged representation of the bracket46. Sloped surfaces 68 are provided in aperture 48. To stop the gearchange hub, recesses 52, 54 and 56 are provided. Through the aperture72, screw threads can be passed in order to fasten the bracket 16 on agear change hub.

FIG. 7 shows a locking device with the sliding rail 36 which has alocking pin 42 and a sleeve 38 in which lies a coil spring (not shownhere). The sliding rail 36 has two sloped surfaces 70 in order that thesliding rail 36 can be more easily pressed back by a point 64 of theshifting pin 30.

FIG. 8 shows a shifting pin 30 with a point 62 which engages in thebracket 46 and with a point 64 which presses upon the sliding rail 36.

REFERENCE NUMERALS

-   2 shifting system-   4 transmission housing-   6 shifting shaft-   8 support-   10 support-   12 axis of rotation-   14 shifting mechanism-   16 gear change hub-   18 gear change hub-   20 gear change hub-   22 shifting fork-   24 shifting fork-   26 shifting fork-   28 shifting fork-   30 shifting pin-   32 shifting pin-   34 slot-   36 sliding rail-   38 sleeve-   40 coil spring-   42 locking pin-   44 recess-   48 aperture-   50 screw-   52 recess-   54 recess-   56 recess-   58 piston-   60 coil spring-   62 point-   64 point-   66 shifting fork-   68 surface-   70 surface-   72 aperture

1. Shifting system (2) for a vehicle transmission in a transmissionhousing (4) which comprises one shifting shaft (6) upon which at leastone gear change hub (18) is movably situated and which has at least oneshifting pin (30) which is rotatable with said shifting shaft (6) aroundan axis of rotation (12) and is movable with the shifting shaft (6)along the axis of rotation (12) and which, at the same time depending onthe rotation of the shifting shaft (6), moves the gear change hub (18)with the shifting shaft (6), characterized in that said shifting pin(30), which upon shifting moves the selected gear change hub (18), isplaced outside said gear change hub (18).
 2. Shifting system (2)according to claim 1, characterized in that said shifting pin (30)engages in a bracket (46) connected with said gear change hub (18) andprojecting out of said gear change hub (18).
 3. Shifting system (2)according to claim 2, characterized in that said bracket (46) projectingout of said gear change hub (18) has recesses (52, 54, 56) in which adetent element (58, 60) engages in the relevant gear change position. 4.Shifting system (2) according to claim 3, characterized in that saiddetent element comprises one coil spring (60) which supports itselfagainst the transmission housing (4) and presses one piston (58) intothe relevant recess (52, 54, 56).
 5. Shifting system (2) according toany one of claims 2 to 4, characterized in that said bracket (46) isfastened on said gear change hub (18) by at least one connecting element(50).
 6. Shifting system (2) according to any one of claims 2 to 4,characterized in that said bracket (46) is cast directly in said gearchange hub (18).
 7. Shifting system (2) according to any one of claims 1to 6, characterized in that said gear change hub (18) has on its outersurface one slot (34) in which a locking device (36, 38, 42) isslidingly situated.
 8. Shifting system (2) according to claim 7,characterized in that said shifting pin (30) lying outside said gearchange hub (18) and associated with said gear change hub (18) which isto be engaged actuates said locking device (36, 38, 42) on the gearchange hub (18) which is to be engaged at the time.
 9. Shifting system(2) according to any one of claim 7 or 8, characterized in that saidlocking device has one sliding rail (36), one locking pin (42) situatedon said sliding rail (36) and engaging in said gear change hub (18) andone receptacle (38) situated on said sliding rail (36) opposite saidshifting pin (30) for a spring element (40) which supports itself onsaid transmission housing (4) and presses said locking pin (42) on saidsliding rail (36) in direction to said gear change hub (18). 10.Shifting system (2) according to claim 9, characterized in that saidreceptacle for said spring element forms a sleeve (38) in which a coilspring (40) is situated.
 11. Shifting system (2) according to any one ofclaims 1 to 10, characterized in that said gear change hub (18) is madeof a plastic material and said bracket (46), said shifting pin (30),said shifting shaft (6) and said locking device (36, 38, 42) consist ofmetal.
 12. Shifting system (2) according to any one of claims 1 to 11,characterized in that said gear change hub (18) is connected with ashifting fork (64) or is part of a shifting fork (64).
 13. Shiftingsystem (2) according to any one of claims 1 to 12, characterized in thatsaid gear change hub (18) is connected with a shifting rocking arm or ispart of a shifting rocking arm.
 14. Shifting system (2) according to anyone of claims 1 to 10, characterized in that all gear change hubs (16,18, 20), all locking devices (36, 38, 42) and all brackets (46) aredesigned equal.
 15. Gear change hub (18) for a vehicle transmissionhaving one shifting shaft (6) connected with a shifting fork (64) or ashifting rocking arm, or integrally comprised by a shifting fork (64) orshifting rocking arm, characterized in that on said gear change hub (18)a bracket (46) is provided which projects from said gear change hub (18)and for gear shifting of the vehicle transmission can be connected withshifting elements (30) on said shifting shaft (60) outside said gearchange hub (18).
 16. Gear change hub (18) according to claim 15,characterized in that on the surface of said gear change hub (18)elements (34, 44) of a locking device are provided.
 17. Gear change hub(18) according to claim 15 or 6, characterized in that said bracket (46)projecting out of said gear shift hub (18) has recesses (52, 54, 56) inwhich a detent element (58, 60) engages in the relevant shiftingposition.